Friction facing



H. BERT FRIGTIQN FACING Jan. 2, 1934.

Filed Dec. 5l, 1931 l lNvENToR HAM/L m/v ABE/Pr BY H l5 ATTORNEYS UNITED STATES. PATENT OFFICE FRICTIQN FACING Hamilton Abert, New York, N. Y., assignor to Baybestos-Manhattan, Inc., Passaic, N. J., a corporation of New Jersey Application December 31, 1931 Serial No. 584,017

6 Claims. (Cl. 15d- 52) 'Ihs invention relates to a friction ring, and made with as high a percentage of asbestos, nor particularly to rings such as are commonly used as tightly woven a fabric, since the stretching in friction clutches, in which the wearing surface action can only be satisfactorily accomplished is made of a high grade woven fabric and is With a comparatively loosely woven fabric and backed with a. material having different characa high proportion of rubber, and With relatively 60 teristics. The friction ring of my invention is innarrow ringS. Furthermore. neel' the innel' edge tended primarily for a clutch facing for autothe fabric is frequently wrinkled so that ridges motive use, but, as will be readily understood, it of tightly Packed asbestos are produced With i11- Will have many advantages in other uses, such as tervening spaces which, after vulcanization, are

lo in various clutches and brakes used in industrial lled with rubber substantially without any as- 55 machinery. bestos. As a consequence, the friction effect is With the development of automotive travel, and non-uniform and Varies aS the material Wears.

particularly with the increased requirements of Again, facings have been made of pulp and Speed and pickup, and the greatly increased commillboard, which in the past have been satisfac- 15 plexity of traic conditions, the importance of tory, but which are less able to meet the difficult 70 smooth engaging and wearing qualities in the conditions of service at present required than are clutch have become of greater and greater imthe high grade Woven faeingS. portance. 'Ihe recent adoption of automatic Accordingly, it is an advantage of the present clutching and free wheeling devices have added invention to produce faeingS having' the desired even more to the importance of the clutch, and qualities of Wearing and Smooth engagement have increased the demand for a superior fric- Which have been attained in the Past only With tion facing for use in automotive clutches. Since the Costly Woven linings out from Whole e10th the demand in current models for lower slung car and to secure these advantages in a much leSS eX- frames prescribes a small limit to the diameter pensive facing than am7 heretofore known of which may be used in clutch discs, and since comparable quality. so the use of single or two-plate clutches is demanded According to my invention, a high-grade facing on grounds of economy, the rigorous requirements comparable in service qualities with the best of clutch operation fall largely upon the fricgrade woven linings can be made by cutting a tion facing, and accordingly the construction and singe disc from undistorted woven asbestos cloth the materials of the clutch facing have come to which has been impregnated with a lowrubber 85 be of the greatest importance. content compound, such for example as has been Prior to my invention, friction facing rings have `used in the best grade of laminated woven clutch been made by playing up rings cut from asbestos facings. A second ring may be formed of pulp, cloth without distortion. These rings have proven for example, by extruding the pulp strip accordmost satisfactory, but because of the excessive ing to the process described and claimed in the 90 wastage which results from this method of man- Novak United States Patent No. 1,785,701 or the ufacture, their cost has, in many cases, been proco-pending application of Amyself and Albert hibitive, and in many cases has led to the use of Whitelaw, Serial No. 376,639, filed July 8, 1929, of inferior materials. which the present application is a continuation Another method which has been adopted is the in part. The pulp, for example, may be extruded 95 shaping of a strip of asbestos cloth or tape so as in a wide strip several times the thickness of the to produce a more or less fiat ring. Thus, a strip fabric ring and at least as wide as the diameter of asbestos cloth, after being coated or imof the ring, and from this strip a ring of correpregnated with rubber, is passed through conical spending diameters, but of greater thickness than rollers geared together so as to produce a comthe fabric strip, may be cut. The two are then 10 pression at one edge of the strip and a stretching superposed and vulcanized, preferably in a. folat the other, and thereby to give to the strip a lower mold, under high mechanical pressure. curved form. This curved strip is then cut to Instead of a pulp backing, other backings may produce a ring of the required diameter, and, be used of materials which are suciently strong with its ends abutting, is placedina suitable mold to hold the woven surface and to absorb and and vulcanized. Although this type of lining has transmit the driving torque which is received by some of the advantages of the undistorted rings said Woven surface, and particularly to hold the out from whole cloth, it is, nevertheless, a much heads of the rivets which are used to securethe inferior product, and cannot be used at all in lining to the clutch plate. For example, millvery wide flanges. It cannot, for example, be board rings impregnated with a suitable binder n@ may be used to back the woven surface ring, and may be cemented thereto either by the cementing action of the rubber, or other binder used in the millboard, or by some other cement used between the two materials. A

With both the millboard and the pulp linings, it is desirable to perform the final hardening treatment in a mold which has projections for forming the countersinks for the rivet heads. In this way, the woven facing will extend beneath the rivet heads, and the strength inherent in the woven fabric will serve to reinforce the pulp or millboard backing beneath the rivet heads. In this way, furthermore, the driving torque will be at least in part ,transmitted directly through the fabric facing to the rivets, and any tendency to longitudinal splitting of the ring will be thereby lessened.

A superior friction ring can also be made by a combination of an undistorted woven facing and a coned woven fabric backing.

In the accompanying drawing, I have shown in Fig. 1 a cross-section through a facing ring made of undistorted woven asbestos fabric and a backing of pulp or millboard.

In Figs. 2 and 3, I have shown a ring made from a facing of undistorted asbestos fabric and a backing of coned fabric.

Referring first to Fig. 1, I have shown a facing ring 10 of undistorted woven asbestos fabric. 'I'his facing ring is preferably made of a medium Weight, closely woven, high-grade asbestos cloth, and is cut preferably in one piece from the whole cloth. The backing ring 11 is composed of a felted asbestos fabric, as for example, either pulp or millboard, and if pulp, 'may be made either by a sheeting process or by an extrusion process, such as has already been described above. The composition of this backing may vary substantially, but preferably contains a relatively small proportion of rubber and a relatively large proportion of refractory filler material which will withstand heat created by the friction when the clutch is -slipped in service. Advantageously this backing is composed largely of short nbre asbestos with' sufdcient binder, preferably rubber or synthetic resin, to hold the backing substantially rigid, and to give additional strength to the material.

In the manufacture ofl this form of ring, the facing of the ring 10 and the backing ring 11', formed as already described, aresuperposed and preferably are placed in a follower mold having projections corresponding to the countersinks 13. This mold is preferably of the follower type, so that the backing may be vulcanized to the facing under pressure, and this pressure causes the binder to ilow sufficiently to mold the cloth ofthe facing ring 10 closely about the countersink projections. Thus, not only is a separate countersink operation avoided, but the facing cloth is m ade to extend beneath the rivet heads, and thereby, as already described, to substantially strengthen their hold upon the facing.

its longitudinal threads running circumferen- In Figs. 2 and 3, I have shown a backing which is composed of the facing ring 10, similar to the corresponding facing ring of the form shown in Fig. 1, and a backing 12 of folded and coned asbestos cloth. The facing ring in this case, as in the embodiment shown in Fig. 1, is preferably cut from a high grade medium weight asbestos cloth impregnated with a low rubber content composition and, as in the case of Fig. 1, is preferably cut in a single piece from the whole cloth. The backing 12 is composed of a more loosely woven asbestos cloth impregnated with a higher proportion of rubber. A strip of this cloth approximately twice the width of the ring 10 is folded double, and is then passed between a pair of cone rollers in the usual manner, as already described above, and in this way the strip is stretched along one edge and compressed and creased at the other edge until it assumes approximately a circular shape. It is then cut to the desired length and its ends abutted so that it forms a ring of substantially the same size as the ring 10. The two are then placed together, preferably in a follower mold, and are vulcanized under pressure in the same manner as described in Fig. 1.

Although I have above described and illustrated in the drawing two specific embodiments of my invention, and have suggested certain-modications thereof, it will be readily understood by those skilled in the art that many other changes and modifications may be made without depart' ing from the scope of this invention.

What I claim is:

1. A friction facing ring comprising a surface ring cut from an asbestos cloth fabric and having the threads thereof in substantially undistorted relation, and a backing layer of a material which is substantially not distorted from circular form by circumferential stresses, and which comprises a refractory reinforcing material and a hardened binder, said binder serving also to unite said layers into a strong coherent ring.

2. A friction facing as defined in claim 1, in which the backing is composed of a strip of asbestos cloth impregnated with rubber and coned to circular shape.

3. A friction facing as defined in claim 1, in which the backing is composed of a strip of asbestos cloth impregnated with rubber and having tially of the ring.

4. A friction ring as defined in claim 1, in which the backing is comprised of a felted asbestos composition including a binder;

5. A friction facing as defined in claim 1, in which both the facing fabric and the backing layer are impregnated with a rubber corr-fsition and the two are vulcanized together into a strong coherent ring.

6. A friction facing as defined in claim 1, in which the cloth of the surface ring is depressed around the rivet holes to form a reinforcing under the rivet heads in the countersinks.

HAMILTQN ABERT. 

